The inventors of the present invention previously developed a brake system for braking a rotating shaft of transportation vehicles including automobiles and railroad cars, and machine tools, and filed a patent application for the grant of patent for the brake system (Patent documents 1 and 2).
The construction of this prior brake system will be briefly described with reference to FIG. 34. A first rotating member 2 is mounted on a shaft 1 so as to be axially slidable and to be rotatable together with the shaft 1. A first gear 3 is fixedly mounted on the shaft 1 for rotation together with the shaft 1. A second gear 6 is supported for rotation by a support shaft 5 on a support arm 4, and is engaged with the first gear 3. A third gear 7 is supported on the support shaft 5 for rotation together with the second gear 6 and is engaged with a fourth gear 8 supported on the shaft 1 for rotation relative to the shaft 1. A second rotating member 9 is combined with the fourth gear 8 for free rotation together with the fourth gear 8 on the shaft 1. The revolving speed N1 of the first rotating member 2 is equal to that of the shaft 1. The rotating speed N2 of the second rotating member 9 is different from the revolving speed N1 of the first rotating member 2 because of the step-up or step-down ratio of the gear train of the first gear 3, the second gear 6, the third gear 7 and the fourth gear 8.
When the first rotating member 2 is axially pushed toward the second rotating member 9, as indicated by the arrows P in FIG. 34, to bring a frictional surface 2a of the rotating member 2 into frictional contact with a frictional surface 9a of the second rotating member 9, a frictional force acts between the rotating members 2 and 9. This frictional force slows the rotation of the first gear 3 and the second gear 6. When the first gear 3 and the second gear 6 are locked together, the second gear 6 tends to revolve about the axis of the shaft 1. Since the second gear 6 is supported by the support shaft 5 on the fixed support arm 4, the second gear 6 is unable to revolve about the axis of the shaft 1. Consequently, the shaft 1 is braked to a stop. In this brake system previously applied for patent, the support arm is, namely, a stationary member, and the support shaft 5 brakes the rotating shaft 1. The magnitude of the braking force is controlled by regulating the frictional force acting between the first rotating member 2 and the second rotating member 9.
For example, the second rotating member 9 can be rotated at 1100 rpm when the first rotating member 2 rotates at 1000 rpm by properly adjusting the step-up or step-down ratio of a gear train including the first gear 3, the second gear 6, the third gear 7 and the fourth gear 8. When a braking force is applied to the first rotating member 2 rotating at 1000 rpm by the stationary support arm 4 or the support shaft 5, the rotating speed difference of 1000 rpm needs to be reduced to zero. When a frictional force acts between the first rotating member 2 rotating at 1000 rpm and the second rotating member 9 rotating at 1100 rpm, only a rotating speed difference of 100 rpm needs to be reduced to zero. Therefore, an impulsive force resulting from braking by the frictional force, and a quantity of heat generated in the latter from rotating speed absorption is far lower than those in the former. The brake system previously applied for patent not only can moderate impulsive force generated during braking, but also can suppress frictional heat generation.    Patent document 1: JP 2003-222167 A    Patent document 2: JP 2003-222166 A